Add as bookmark

Are All Fish Oils Equal? - Part I

by David Taylor(more info)

listed in essential fatty acids, originally published in issue 117 - November 2005

Fish oils have received a barrage of positive publicity in recent months, as many people have come to appreciate how this dietary input can be a rich source of life-enhancing Omega-3s. There seem to be few areas that these 'good fats' do not benefit: be it brain function, cardiovascular health, joint pain and a whole plethora of conditions linked to inflammation.

As a result of the interest, the Omega-3 fish oil market has become more competitive, with many manufacturers now entering the market with a great range of differing products. Consumers are quite justified in being confused: there is a great range of oils on offer, with varying differences in price, specification and quality. So what should one be looking for when buying a fish oil, and are all the oils the same?

Fatty Acid Specification

The main Omega-3 long chain fatty acids that one is trying to ingest are EPA and DHA. Choosing the right fatty acid, and the right balance, is vital in order to get the right result. Broadly speaking, DHA plays a more structural role, as part of the walls of cell membranes, so it is really important if one is trying to maintain structural roles such as during pregnancy and early childhood. EPA plays a more functional role in trying to help cells communicate and in various anti-inflammatory roles. There is no complete verdict in the research yet on what is the optimum balance of EPA to DHA, but certainly when buying oil it is advisable to look at how much of any the manufacturer is providing. The usual standard fish oil is called an 18/12. That is, it will have a fairly balanced ratio of 18% EPA and 12% DHA. However, there are concerns that the fatty acids will compete for absorption, and that is why it may be more optimum to take a particular concentration of one over the other. So you may want higher amounts of EPA if you are interested in brain function, and higher DHA for pregnancy. Check the box to see the exact levels of EPA to DHA.

Natural Oils, versus Synthetic

This is an area that has largely slipped under the consumer radar screen, because manufacturers are not obliged in the UK to explain the exact form of the fish oil that they are offering. It can be quite hard, therefore, to know if the form you are taking is natural or synthetic.

If you squeeze a fish and take out the oil, it will be in the natural form as a triglyceride (TG) (as well as diglyceride, or monoglyceride). This presented quite a problem for the oil industry because triglycerides, which are unwieldy molecules, are prone to oxidation (rancidity) and are difficult to concentrate. The solution was to deconstruct the molecule by stripping off the glycerol, and then marry the free fatty acid with ethanol alcohol. This created an ethyl ester (EE), a synthesis of the ethanol and the fatty acid that is more malleable and thus easy to concentrate.

There are many manufacturers now delivering ethyl esters onto the nutritional market at low cost, and the more concentrated specification of the fatty acids, some up to 80%, does make them appear to be an attractive proposition. However, there is a deeper story than that being told on the label: in simple terms 'more' does not necessarily mean better.

When you ingest ethyl esters, they are absorbed in the liver, where the body then breaks away the ethanol alcohol and rebuilds the free fatty acid back into a triglyceride. So there is a concern about a product that leaves residues in the liver, and for this reason it would not be wise to give ethyl esters to children or pregnant women. In fact, ethyl esters used as pharmaceuticals have this express warning on their packaging. But it is a fact that this is a more inefficient means of taking the fatty acids compared with the instant absorption enjoyed when taking oils in the triglyceride form. Various papers have shown greater efficacy with TG forms over EE, so on balance it would seem preferable to opt for the more natural route.

How do you know if the oil being offered is natural or synthetic? If the manufacturer does not clearly state the form on the box, it is still quite easy to evaluate. Firstly, natural oils rarely have more than 30%, so very high concentrates are invariably ethyl esters. Secondly, the synthetic oils usually have fatty acid ratios that are not represented in the food chain: they may have completely elevated levels of EPA, and no DHA.

In my next article I will be looking at three other areas that we should be interested in when choosing an Omega-3 fish oil; delivery methods, environmental contaminants and efficacy.

For a good example of how independent research has proven the effects of fish oil, you can visit the website and read about the Durham LEA Trial.


  1. No Article Comments available

Post Your Comments:

About David Taylor

David Taylor is a psychologist with a background in psychopharmacology and development. From working with children he developed an interest in the effects of environmental factors, particularly the effects of nutrition, upon mental and physical health. He is co-director of Optimum Nutrition North East in Durham City, with his wife Sandra, a health psychologist. They take a holistic approach to health and wellbeing focussing upon nutrition, stress and lifestyle. For more information about Optimum Nutrition North East and the services and products available Tel: 0191 3849088; E:; W:

  • mycology research MRL

    MRL markets mushroom products food grade US & Netherlands GMP standards. Health Professional Videos

  • nutrition and cancer

    by Sandra Goodman PhD The latest scientific research regarding Nutrition and Cancer. Full details at

  • Seaweed as Superfood

    Comprehensive nutrient balance found in no other natural food but seaweed: colon health, weight loss

  • Liposomal Nutrients

    Optimum system for nutrient delivery to cells - fully bioavailable vitamins absorbed and metabolised

top of the page